In a crossed aldol condensation (condensation between aldehyde and a ketone), the primary products are such, that the carbonyl group of the ketone remains intact, and the $\alpha$-hydrogen of ketone participates, i.e. gets removed by the base to form the resonance stabilised nucleophilic enolate which later attacks the aldehyde. These are formed together with the self-condensation products, but the reverse products (aldehyde-derived enolate + ketone) are rarely formed.
I had a look at the mechanism, and also how a base catalyses condensation by favouring enolate formation.
Why is the ketone involved in enolate formation and not aldehyde in crossed/mixed aldol-condensation reactions?